UPPER MERION — Valley Forge National Historical Park commemorated the 236th anniversary of the arrival of General George Washington’s troops to the area with a free event for the public Thursday. Visitors were treated to ranger-led walking tours, outdoor living history demonstrations, educational activities, colonial carolers and more during the park’s commemorative event. Washington’s troops established their encampment at Valley Forge on Dec. 19, 1777 and stayed for six months before leaving for battle.